1. Field of the Invention
The invention is related to the field of weather technology, and in particular, to precipitation measurement devices.
2. Statement of the Problem
Some existing precipitation gauges maintain two heated plates at the same constant high-temperature. The two plates are exposed to the same ambient temperature and wind, but only one of the plates is exposed to falling precipitation. The other plate is shielded from the falling precipitation. Thus, the plate that is exposed to falling precipitation requires more power to evaporate the falling precipitation and maintain the constant temperature. Thus, the power differential between the two plates correlates to the precipitation rate.
In practice, these heated precipitation gauges may require an expensive power switch and complex feedback loop to maintain the plates at the high constant temperature. The feedback loop may turn the heat on and off many times a second, so the actual plate temperature may not properly converge on the desired constant temperature. Instead, the actual plate temperature may oscillate around the desired constant temperature. This oscillation causes a loss of sensitivity and may lead to instability during a significant precipitation event.
The rapid on/off switching may require a large and stable power supply. The power supply must constantly provide power, since both plates are continuously maintained at the high temperature. Thus, the heated precipitation gauges may require expensive power supplies that must continuously provide power. This continuous power consumption adds additional cost.
In addition, some precipitation tends to bounce off of the exposed plate instead of collecting on the plate. The precipitation that bounces off the exposed plate does not effectively cool the plate, so minimal power is consumed by precipitation that bounces off the plate. The power consumption is correlated to the precipitation rate, so a power consumption measurement that is incorrectly low due to bouncing precipitation causes the resulting precipitation rate measurement to be incorrectly low as well.